Ammonia is a highly toxic and corrosive gas that is a key component within the agriculture and chemical industries. It is heavily produced for its essential role in fertilizer within agriculture, and also found as a significant emitted compound from livestock and wastewater. Even at low concentrations, ammonia can negatively impact the growth and health of livestock as well as the well-being of industrial workers that are responsible for its transportation, use, and removal. The US Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) for ammonia at 50 ppm, highlighting the need to separate any appreciable concentration of ammonia from air. Due to its small size and high vapor pressure, ammonia remains a challenging gas for common adsorbents to adequately remove at ambient conditions.
For high vapor pressure gases such as ammonia, physisorption interactions are typically not strong enough to promote high adsorption loadings. As a result, many small, high vapor pressure toxic industrial chemicals (TICs), such as H2S, SO2, and NH3 are of primary concern for emergency and military personnel due to their high toxicity and inability to be effectively removed by many adsorbents. The removal of NH3 from air is particularly important due to its pervasive use in the fertilizer and waste treatment industries, as well as its low permissible exposure limit (PEL) of 50 ppm.
Porous carbons have long seen pervasive use within the gas separation and purification industries due to their low cost, wide chemical and thermal stability, and high bulk porosity Over the past few decades, carbon materials have garnered great attention as catalyst supports, sorbents, electrodes, etc. due to increased control over their pore structure through the use of nanocasting and other synthesis approaches. In addition, increasingly ordered carbon structures, such as SWNTs, graphene, fullerenes and nanodiamond, have been investigated due to great inherent tribological and conductive properties. A new class of highly tailorable nanoporous carbons, carbide-derived carbons (CDCs), has also recently been established. These materials are produced through the selective extraction of a metal or heteroatom from a carbide precursor, commonly by halogenation. The resulting nanoporous carbon exhibits large specific surface areas and a high degree of microporosity.
There has been growing interest to functionalize CDCs with metal nanoparticles. Many traditional methods focus on impregnation of the metal by wetting the adsorbent with a solution containing the metal precursor. However, this often results in limited control of metal particle size, pore blockage of the carbon support, and weak support-metal interactions, particularly within templated pore architectures that rely on interconnecting pores.
There remains a need for improved carbide derived carbons and methods of making thereof that overcome the aforementioned deficiencies.